Installing a passage door in a building often requires the installer to adjust the exact position of the door in the frame so that the hinge edge of the door can freely swing open without binding and the catch side of the door is precisely aligned with the corresponding catch when closed, so that the latch or lock properly engages with the corresponding hardware on that side of the door frame. Most residential passage doors are now sold “pre-hung” while commercial doors are purchased as a “package” together with a separate frame, etc. A carpenter “sets” this door frame into the wall structure onsite. Wall finishing (drywall, panels, etc.) is then applied around the frame. Finally, hardware and the door are installed in the frame. That is, the door and door frame are purchased or shipped as a unit. The door frame, preferably with the door in place, is installed in the rough opening. The door frame and the door are thus created as a matched set. Despite this, the process of fastening the door frame in the rough opening can cause the door frame to distort slightly. Even such slight distortions can require that the door be adjusted slightly so that the latch and sealing functions of the door perform smoothly. A shim, which is a thin, relatively inexpensive, relatively incompressible piece of card stock usually, suffices to make such final adjustments. If there is too great of a gap on the strike portion of the installed door, the installation screws on the door-side of the hinge are usually unscrewed enough to permit one or more of the shim cards to be inserted between the hinge plate and the door. To move the hinge towards strike side of the door frame, one inserts the shim card stock between the back side of the hinge mortise and the back side of the hinge plate at a location near the hinge knuckles, and retightens the mounting screws. This moves the hinge knuckles towards the strike side of the frame. This is done to as many hinges as necessary to achieve desired reveal at the door edges. Moving the hinge knuckles towards the strike side of the frame hopefully closes the previously oversized gap on the strike side of the door.
Similarly, to provide a larger gap on the strike side on a mounted door, the hinge plates on the door frame are loosened by unscrewing the mounting screws and one or more pieces of shim card are placed along the free edge of the hinge plate. When the screws are tightened again, this positions the hinge knuckles further away from the strike side of the frame, and a slightly larger gap on the strike side hopefully results.